Electrical instrument.



0. HALL, ELECTRICAL INSTRUMENT.

APPLICATION FILED JUNE 23,1914.

LQMAMB Patented July 24, 1917 2 $HEETS-SHEET I.

Inventor: C ester I. Hall.

His QTttorney.

C. I. HALL.

ELECTRICAL INSTRUMENT.

APPLICATION HLED JUNE 23.1914.

1 34,443 Patented July 24 1917.

2 SHEETSSHEET 2.

Witnesses Q lm/entor"; Y Chester 1. Hali,

' H is A'btomeg.

ASSIGNOR T0 GENERAL ELECTRIC OF NEW YORK.

ELECTRICAL INSTRUMENT.

Specification of Letters Patent.

Patented July 241, 191i '1.

Application filed June 23, 1914. Serial No. 846,786.

To all whom it may concern:

Be it known that I, CHESTER I. HALL, a citizen of the United States, residing at Fort Wayne, county of Allen, State of In- 5 diana, have invented certain new and useful Improvements in Electrical Instruments, of which the following is a specification.

y invention relates to electrical instruments, and especially to electrical measuring instruments, such, for example, as are employed for indicating electrical demand and in particular the maximum demand of an electrical installation. The object'of my invention is to provide a novel and improved form of electrical instrument. More particularly the object of my invention is to provide a simple, inexpensive and satisfactory electrical demand indicator. Further objects of my invention will be noted hereina-fter.

The novel features which I believe to be patentably characteristic of my invention will be definitely indicated in the claims appended hereto. The principle of my invention and the mode of operation of electrical instruments embodying the same will be understood, from the following description taken in connection with the accompanying drawings, in which:

Figure 1 is a diagrammatic perspective view of a maximum demand instrument embodying my-invention, Fig. 2 is a diagrammatic perspective view of a modified form of demand instrument. Figs. 3 and 4 are detail elevation and plan views respectively illustrating certain features of construction of the instrument shown in Fig. 1; Fig. 5 is a detail view of the recording device of the instrument shown in Fig. 2; and Fig. 6 is a detail view of the marking stylus used in connection withthe instrument of Fig. 1.

Broadly my invention involves the principle of the balancing of two torques adapted to act upon the same movable member. One of these torques hereinafter called the energy torque, is controlled by the flow of energy in an electric circuit, and the other torque, hereinafter called the variable torque, is adapted to be varied until it equals and balancesihe energy torque. The variable torque is controlled by the movement of the movable member so that for a predetermined energy flow a definite movement of the memher is required to adjust the value of the variable torque until it equals and balances constant as long the energy torque. The time required for the variable torque to equal and balance the energy torque can be determined by providing suitable operative connection between the movable member and the variable torque producing means, and in this manner the instrument can be given a time lag of any desired length. In accordance with my present invention the two torques are caused to act directly upon the same member, and to operate similarly through the same operative connection. Thus the movable member may be operatively connected to any suitable indicating or-recording means and the two torques will act directly on the movable member so that the point of application of the force actuating the movable member and the indicating or recording means will always be at the same point in the operative connection between the member and the indicating or recording means. Again, in accordance with my present invention the two torques are of the same character, that is, both are electrical torques developed by electromagnetic instrumentalities.

11 carrying out my invention I provide a movable member adapted to be acted upon by two operatively opposing electrical torques. That is to say, one torque acts positively and the other negatively, or as a countertorque. The positive torque is the energy torque and is controlled by the How of energy in an electric circuit and remains as the energy flow remains uniform. The countertorque is the variable torque and is so controlled by the movable member that its value is increased or diminished in accordance with the direction of movement of the movable member and so that it always tends to equal and balance the positive torque thus causing the movable member to come to rest. In the practical embodiment of my invention, I provide an electrodynamometer having a torque producin element controlled by the flow of electric energy in an electric circuit and a variable countertorque producing element. These two torque producing elements may obviously have certain common mechanical and'electrical features combined in a substantially single instrument, or p the two torque producing elements may be entirely independent units, and I have herein used the term electrodynamometer broadly without regard to whether the two torques are ber.

developed by combined or independent electrical torque producing elements. 0

The torque and countertorque producing elements of the electrodynamometer are adapted to act upon the same movable mem- In order to suitably control the speed of movement of the member damping means is provided therefor. This damping means may be produced magnetically by-a permanent magnet or may be produced by the torque producing elements of the electro dynamometer. My novel form of instrument thus comprises an electrical torque producing element and an electrical countertorque producing element adapted to act upon the same movable member and damping means for the member. The torque producing element is controlled by the flow of energy in an electric circult and the countertorque producing element 1s controlled by suitable connection, preferably reducing gearing, with the movable member. Movement of the movable member thus varies the value of the countertorque until it equals and balances the torque, whereupon the movable member comes to rest and remains in this position until an unbalancing of the two torques is brought about by .a change in the energy flow in the circuit. The resulting movement of the movable member due to the unbalancing of the two torques again effects an adjustment of the value of the countertorque until the two torques are again equal and the member brought to rest, and this operation .is repeated whenever the two torques become unbalanced. It will thus be evident that when the value of the positive torque is dominating the movable member will move in a positive or forward direction thereby increasing the value of the negative or countertorque until the latter equals and balances the positive torque. When the value of the countertorque is dominating, the movable member will move in a negative or backward direction thereby diminishing the value of the negative or countertorque until the latter equals and balances the positive torque.

The movement of the movable member may be employed in any desired way to secure an indication or record of the characteristic to be measured. As a demand indicator the movable member may actuate a non-return pointer or may operate a recording stylus to graphically indicate the maximum movement of the member, and asan indicating instrument the movable member may be operatively connected to an indi cating pointer. Other applications of my invention and means for employing the movement of the movable member for effecting various electrical measurements will be apparent to those skilled in the art.'

My invention will be best understood by reference to the accompanying drawings which illustrate two practical embodiments of the invention in demand instruments. Referring first to Fig. 1 there is shown a rotatable disk armature member 5. This armature member is similar to the disk armature employed in the well known induction watthour meter, and consists of a circular metallic disk of conducting material, such as copper or aluminum. The armature is secured to a pivotally mounted shaft 6. The torque producing elements adapted to act upon the armature 5 are independent in the modification shown in this figure and consist of an induction watthour meter element and an induction motor element of the shaded pole type. The induction meter element comprises a laminated magnetic core 7 having a potential coil 8 operatively mounted thereon, and a second oppositely positioned laminated magnetic core 9 having two series or current coils 10 operatively mounted thereon. The disk armature is operatively arranged in the usual manner in the air gap between the two magnetic cores 7 and 9. The coils 8 and 10 are electrically connected to the conductors 11 of an alternating current electric installation supplying electric energy to translating devices 12. The torque developed by the induction meter element is thus controlled by the flow of energy in the conductors 11 of the installation. The arrangement of the induction meter element is such that the torque developed thereby is a positive torque adapted to rotate the armature memberin a positive or forward direction, that is clockwise, as viewed from the top in Fig. 1.

The induction motor element is arranged to exert a countertorque upon the armature member 5, and is thus adapted to rotate this member in a negative or backward direction. The induction motor element in the form here shown is of the shaded pole type and comprises a U-shaped magnetic member 13 having a current carrying coil 14 operatively positioned on each leg thereof. The coils 14 are connected across the conductors 11, and are thus in effect potential coils. A shading pole tip 15 is secured to the lower leg of the U-shaped magnetic member 13 and carries a' short circuited copper coil 16. Directly above the shading pole tip 15 and separated therefrom by a small air gap is a second pole tip 17 having a short circuited copper coil 18 carried thereby. The armature member 5 is arranged to rotate in the air gap between the two pole tips 15 and 17, and the pole tip 17 is secured to a rotatable shaft 22 so that it can be moved with respect to the pole tip 15. The arrangement is such that when the two shading coils are electrically in opposition no torque isdeveloped by the induction motor element, but when the shadmeager.

maximum torque will be acting upon the disk armature and tending to rotate the armature in a counterclockwise direction.

The pole tip 15 is secured to the magnetic member 13 by means of a screw 60. The position of the pole tip 15, and more particularly the position of the short circuited coil 16, with respect to the magnetic member 13 is first adjusted and then the screw 60 tightened. thereby firmly securing the pole tip in the desired adjusted position. The pole tip 17 is adapted to be secured to the shaft 22 in the desired adjusted position by means of a set screw 61. The adjustments of the pole tips will be discussed in greater detail hereinafter.

A U-shaped bundle of magnetic laminations 29 is secured to the ends of the U- shaped magnetic member 13, and constitutes a magnetic shunt around the air gap between the pole tips 15 and 17 and serves to control, the flux passing through the armature member 5. This magnetic shunt thus serves as a calibrating member for changing the value of the torque generated by the induction motor element, so that the pointer may be brought to any particular position on the scale. The variation in position and in effect of this shunt varies uniformly the total flux which is used for damping and the torque generated by the motor element, so that for an increased deflection the speed of rotation will be increased proportionally, thus maintaining a constant time interval. The effect of the magnetic shunt 29 can be varied by means of the adjusting screws 72 and 73.- These screws serve to adjust the position of the shunt member 29 with respect to the U-shaped magnetic member 13 so that the reluctance of the magnetic circuit between the adjacent surfaces of these members can be varied. This affords a convenient and simple means for adjusting the' effect of the magnetic shunt in the calibration of the instrument.

The shaft 6 drives a gear member 19 through a train of reduction gearing 20. The gear member 19 drives a sector shaped gear 21 secured to the shaft 22, to which latter the movable pole tip 17 is also secured. Movement of the sector shaped gear 21 thus varies the position of the pole tip 17 with respect to the pole tip 15. The arrangement is such that rotation of the armature member 5 in a positive orforward direction effects a clockwise movement of the pole tip 17 thereby increasing the negative or counter torque due to the shaded pole induction motor element, and on the other hand rotation of the armature member 5 in a negative or backward direction effects a counterclockwise movement of the pole tip 17 and decreases the countertorque developed by the induction motor element.

The gear member 19 may be employed to actuate any suitable indicating or recording means. In Fig. 1, I have shown the gear member 19 meshing with a gear A pointer member 24 is operatively connected to the gear 23 and carries a marking s-.ylus 25 adapted to sweep across a suitable record chart 26. The marking stylus is in engage ment with the record chart and is adapted to impart a graphic indication of its movement across the record chart. Preferably the record chart is of specially prepared paper adapted to have a black mark imparted thereon by the passage of a metallic stylus thereover. The marking stylus 25 is thus of brass, or similar metal, and is screwthreaded into a boss 75 secured to the pointer member 24:, as will be best seen in Fig. 6 of the drawings.

It will be seen from the foregoing description that the instrument illustrated in Fig. 1 consists essentially of a standard watthour meter having in place of the permanent magnets a U-shaped electromagnet with its coil connected across the line, and in place of the standard register a gear train leading from the meter armature to the recording stylus and to the upper pole tip of the U-shaped magnet. The U-shaped magnet provides the necessary damping for the meter armature for both directions of rotation, and in addition is adapted to act as a shaded pole motor element to exert upon the armature a variable countertorque controlled by the rotation of the armature. The operation of the instrument will, it is believed, be understood from the foregoing discussion and description. The following concrete example, however, may be helpful in further understanding the operation of the instrument and the nature of the record or indication obtained thereby.

Assume the instrument to be in its initial or zero position, that is, the rotatable pole tip 17 acting in opposition to the stationary pole tip 15 with no load on the meter. The initial or zero position of the disk armature member 5 and of the indicating member 24 is determined when the relatively movable pole tips occupy this position. Under this condition the armature will be stationary. If now a load of 5 KW is thrown upon the instrument, a torque proportional to this load will be generated by the shunt and series motive elements of the meter and the armature will start to rotate in a positive direction at a speed proportional to this load, the damping being effected by the total flux of the U-shaped magnetic member 13 passing through the disk armature. As the armature rotates, the rotatable pole tip 17 is gradually moved away from the position of zero countertorque toward a position of countertorque that will exactly equal and balance the positive torque of the meter element. When such a condition is reached an.

.tation will move position of lower and lower torque until exact balance will be established and the meter armature will remain stationary. The position at which the rotatable pole tip is then standing, and consequently the position of the indicating member 24., will be proportional to a load of 5 KW. The length of time required to move the pole tip from the zero position to the position of balance is dependent upon the gear ratio between the meter armature and the rotatable pole tip, and can obviously be made of any desired length. If the load is now increased to 6 KW, the torque of the meter element will be greater than that of the U-shaped motor element and rotation in a positive direction will again begin and will continue until the rotatable pole tip has arrived at a second position where the torque developed by the U-shaped motor element is equal to the torque of the meter element. Assume now that after such a new balance is reached the load is entirely removed, thus causing the torque of the meter element to fall to zero. The countertorque of the U- shaped motor element, however, is still at a value equivalent to 6 KW. The disk armature will, therefore, begin to rotate in a negative or backward direction. Such rothe rotatable pole tip to a finally the two pole tips are in exact opposition when rotation of the armature will cease. It-will be obvious that the torque and countertorque are both applied directly to the meter armature 5 and act similarly through the same gear train.

The record is made by means of the passage of the stylus 25 over the record chart 26. The position of the stylus with respect to the record chart is a measure of the flow of energy in the circuit at any time when the armature is at rest, or in other words, when the torque and countertorque are equal and "balanced. The maximum movement of the stylus'is thus a measure of the maximum energy flow in the circuit and of the maximum demand of the installation. any desired period can be ascertained by the length of the line drawn on the record chart by the marking stylus; The record chart is designed to be removed from the instrument at the end of the period of measurement of the demand and a fresh one substituted therefor. To this end the record chart is provided with holes which are adapted to register with holes in a supporting member 27. A pin 28 having an enlarged head passes through the registering holes and is frictionally held in position, thus securely and accurately positioning the record chart.

' It will be understood by those skilled in the art that the countertorque developed by the U-shaped motor element can be varied The maximum demand over by altering the position of the short circuited coil of, the shading pole. Turning the pole tip 15 about its axis will thus alter the position of the short circuited coil 16 with respect to the magnetic member 13 and will thereby vary the countertorque due to this shaded pole-tip. This affords a very convenient means for calibrating the instrument since the countertorque developed by the U-shaped motor element can be altered by adjusting the position of the pole tip 15. Both the adjustment of the pole tip 15 and the adjustment of the efiect of the magnetic shunt 29 can thus be employed in the calibration of the instrument. The screw 60 serves to secure the pole tip 15 to the magnetic member 13 in the desired adjusted position.

Itwill further be evident that the rate of change of the countertorquecan be varied by suitably selecting .the position of the are of movement of the pole tip 17 with reference to the magnetic member 13 and the adjusted pole tip 15. To this end the pole tip 17 is designed to be adjusted about the shaft 22 as a pivot and is secured in its adjusted position by means of the set screw 61. By adjusting the position of the pole tip 17 therate of change of the countertorque due to the movement of the pole tip can be varied, and further a difierent rate of change of the countertorque for different positions of the pole tip can be produced. Thus the change in the countertorque effected by a predetermined number of revolutions of the armature member 10 may be made smaller when the actual value of the countertorque is small than when the actual value of the countertorque is large, and, accordingly, a greater number of revolutions of the armature member will be necessary when the actual value of the countertorque is small to produce the same change in the instrument can be changed.-

In Fig. 2 of the drawings I have shown a modified form of instrument embodying my invention. The instrument comprises a rotatable armature member 35, of the same character as the rotatable member 5 hereinbefore described, adapted to be acted upon by two operatively opposing electrical torques. A laminated magnetic core 37 has a potential coil 38 operatively mounted thereon. A second laminated magnetic core 39 is positioned opposite the core 37 with an air gap between the cores to accommodate the disk armature 35. The core 39 has two legs upon one of which is mounted a current coil- 40- connected in series relation with the conductors 58 of the installation. The other leg of the core 39 has a aaeaaee coil 41 operatively mounted thereon, and this coil is connected to the secondary wind ing 42 of an induction regulator. The coil 41. is designed when a current flows therethrough to exert a torque tending to rotate the disk armature member 35 in a direction opposite to the direction of rotation due to the effect of a current flowing in the coil 40. Thus a flow of current in the coil 40 is adapted to rotate the armature member in a positive or forward direction whereas the: flow of current in the coil 41 is adapted to rotate this member in a negative or back. ward direction. The rotation of the armature member 35 in either direction is damped by permanent magnets 50 in the usual manner. 1

The induction regulator has a primary winding 43 connected in shunt relation to the conductors 58. The primary winding 43 of the induction regulator is mounted on a stationary magnetic core 44 while the secondary winding 42 of the induction regulator is mounted upon a movable magnetic core 45. By turning the magnetic core 45 the inductive relation between the primary and secondary windings of the induction regulator is varied whereby the current supplied to the current coil 41 is also varied. The magnetic core 45 is connected by reduction gearing 46 to the rotatable shaft 36 of the induction meter element, so that rotation of the armature member 35 effects a movement of the core 45 thereby varying the current flowing in the coil 41.

The operation of the instrument illustrated in Fig. 2 is as follows: Starting from no load condition the secondary winding of the potential regulator is in a neutral position and no current is induced therein, hence no current flows in the coil 41. Assume that a constant load is thrown on the meter. The armature member 35 will immediately begin to rotate in a forward or positive direction at a speed proportional to the load. As the armature rotates, however, it varies the position of the secondary winding 42 through the cotiperation of the reduction gearing 46 and a current is induced in this windingwhich gradually increases as the member 35 rotates forwardly. The current coil 41 is so arranged that a flow of current thereinresults in the development of a countertorque tending to oppose the rotation of the armature member 35 in a forward direction. As the member 35 continues to rotate the current flowing in the coil 41 gradually increases, thus increasing the countertorque due thereto and decreasing the speed of rotation of the member 35. This condition will continue until the member 35 has turned the secondary coil 42 of the potential regulator to a position at which the current supplied to the coil 41 develops the same num er of ampere turns as is developed by the coil 40..

When the ampere turns of the two coils on the, current yoke of the meter are exactly equal and opposite in effect, the rotatable member 35 will come to rest. Assume now that the load is decreased. The ampere turns in the current coil 40 of the meter will be similarly decreased while the ampere turns of the coil 41 will be of the same value as before. The countertorque is, accord- 7 5 ingly, now dominating and the member 35 will, therefore, rotate in a negative or backward direction,at the same time moving the secondary coil 42 so as to decrease the current flowing in the coil 41. This operation so will continue until the. ampere turns of the coils 40 and 41 are again balanced and the movable member 35 has again come to a standstill. It will be apparent, therefore, that by placing any .suitable indicating means, such as a pointer, on the shaft of the movable magnetic core of the induction regulator an indication of the demand may be obtained. By properly arranging the ratio of gearing between the armature member 35 and the movable shaft of the regulator it is possible to obtain any time interval which may be desired.

In Fig. 2 I have illustrated a graphic recording device'which suitably records a plurality of the maximum demands. The shaft of the magnetic core 45 of the induction regulator drives a pinion 51. The pinion 51 meshes with another pinion 52' secured to the same shaft as a pointer member 53. The 150 pointer member carries near its end a screwthreaded marking stylus 63 which is arranged to sweep across a circular record chart 54. An eccentrically mounted pawl 55 is carried by the pinion 51 and engages in the serrated edge 56 of the carrier for the record chart. When the magnetic core 45 is turned in a positive direction by the armaturemember '35 the pawl 55 engages between the serrations of the carrier and -moves the latter through a small angle.

When the magneticcore is turned in a backward direction, the pawl 55 rides idly over the serrations. The recording chart 54 is thus moved through a small angle whenever the armature 35 rotates in a positive or forward direction, but remains stationary when the armature rotates in a negative or backward direction. A pawl 57 is operatively positioned with respect to the serrated edge 56 and is adapted to prevent backward movement of the carrier for the record chart. It will thus be seen that a saw-tooth type of record is obtained in which the value of the maximum demands can be readily ascertained. v

The record chart is designed tobe removed from its carrier and to facilitate this .operation the pointer member 53 is flexible to permit the convenient movement of theme marking stylus away from the record chart. A bifurcated yoke 62 is secured to the shaft of the core 45 and the pointer member 53 is pivoted thereto, as will be clearly seen in nected between the yoke and the pointer member and normally maintains the mark ing stylus 63 in contact with the record chart. It will be observed from Fig. 5, however, that the pointer member 53 can readily be moved toward the left, that is counterclockwise, and that when it has been moved through a certain angle the spring 59 will operate to hold the pointer member in substantially a horizontal position, which position is determined by the engagement of the pointer member with the shoulder 64: of the yoke.

It will be .apparent from the foregoing description that I have provided agnovel form of electrical instrument having'a movable member arranged to be directly acted upon by two electrical torques. The instru' I ment may obviously be constructed for single phase or polyphase circuits of any frequency and in any capacity, and either selfcontained or with standard potential and current transformers. The instrument contains no contacts, no opening of gearing, no

escapements, and no other electrical or mechanical connections which are inherently subject to change of condition or failure. Furthermore, there is in the instrument, no clock movement, motor, or other constantly rotatin device. Instruments which depend for their continuous operation upon a constantly moving part are subject to excessive wear, which means short life and liability of failure. In the instrument of my invention no motion whatever takes place except when there is a change in the condition of the load which the instrument is indicating. In commercial practice this means I that about ninety per cent. of the time the instrument is practically at rest. The major part of the instrument consists of a standard watthour meter and all adjustments and methods of calibration are similar to those found on the watthour meter. This makes it unnecessary to educate a corps of men in the repair and maintenance of the device, since the operators are already familiar with the meter which is used as the basis of the instrument.

The instrument further contains no s rings or other torsion members which are llable to temperature variations, breakage, chan 'ng after continued service, and similar o jectionable failin 8.; Calibration of the instrument is depen ent only upon the exact balance of two electrical torques. The instrument is entirely self-contained and is connected into a circuit as is the standard watthour meter, being usually connected in 85 series with the watthour meter of the inig. 5 of the drawings. A spring 59 is con-' stallation. All variables in-the instrument are adjustable. The scale setting and time interval are both capable of accurate. calibration, and the time interval may be .changed from one minute to one hour by a simple change of gear ratio. It is impossible under any condition for the instrument to record a value higher than that of the consumers demand, so that entire confidence may be placed in the record obtained. Unlike the demand indicators now available, the instrument gives a permanent record of the demand instead of the indication of a friction pointer or similar device which is returned to zero at the end of the demand period. The permanent record is posslble with this instrument because of the extremely high torque developed, which means entire freedom from the effect of variable friction. Furthermore, the instrument gives 5 readings over an elapsed time interval so that the largest demand is recorded.

Various applications of the principle of my present invention will be apparent to those skilled in the art. Numerous modifica- 99 tions in theconstruction and design of instruments of the type herein illustrated without departing from the spirit of my invention will also be evident to those skilled in the art. I do not wish, therefore, to be 5 limited to the specific application or to the details of construction herein illustrated by -way of example, but I aim in the appended claims to cover all modifications of my invention within its spirit and scope.

What I claim asnew and desire to secure by Letters Patent of the United States, is

1. An electrical instrument comprising a rotatable member, means for developing a torque adapted to turn said member in a forward direction, an induction motive element having a movable shading pole adapted to rotate said member in a reverse direction, and means operatively connecting said shading pole to said rotatable member so that rotation of the member operates to vary the torque of said induction motive element until the member comes to rest.

2. An electrical instrument comprising a rotatable member, means for developing a torque adapted to turn said member in a forward direction, an induction motive element having a movable shading pole adapted to rotate said member in a reverse direction, and gearing operatively connecting said shading pole to said rotatable member so that rotation of the member operates to vary the torque of said induction motive element until the member comes to rest, said gearing being proportioned to provide a desired tlme interval before the member comes to rest. 1

3. An electrical instrument comprising a rotatable disk armature, induction motive means operatively related to said disk armaasagna ture and adapted to produce a direct torque depending upon the energy flow in an elec'-" tric circuit and a variable countertorque, and means controlled by the rotation of said disk armature for varylng the countertorque produced by said induction motive means until it equals and balances the direct torque of said means.

4. An electrical instrument comprising a rotatable disk armature, and induction motive means operatively related to said armature and adapted to develop a torque and a countertorque tending to turn said armature in a forward and a reverse direction respectively, said torque being dependent upon the energy flow in an electric circuit and said countertorque being controlled by the rotation of said armature.

5. An electrical instrument comprising a rotatable disk armature, induction motive means operatively relatedto said armature and adapted to develop a direct torque and a countertorque tending to turn said armature in a forward and a reverse direction respectively, means for varying the countertorque developed by said induction motive means, and gearing operatively connecting said armature to said last mentioned means whereby the countertorque is varied until it equals and balances the direct torque of said induction motive means.

6. An electrical instrument comprising a rotatable member, electrical means for producting a torque and a countertorque adapted to act upon said member, said torque being controlled by the flow of energy in an electric circuit, and means operatively connecting said member to said countertorque producing means whereby on a predetermined energy flow in said circuit said rotatable member is required to make a given number of revolutions to cause said countertorque to equal and balance said torque.

7. An electrical instrument comprising a rotatable disk armature, induction motive means operatively related to said armature and adapted to develop a torque and a countertorque tending to turn said armature in a forward and a reverse direction respectively, said induction motive means having a movable shading pole adapted to vary said countertorque, and means operatively connecting said armature to said shading pole whereby said countertorque is varied until it equals and balances said torque.

8. An electrical instrument comprising a rotatable member, electromagnetic means adapted to rotate said member in a forward direction, electromagnetic means adapted to rotate said'member in a backward direction, said member being arranged to make a plurality of complete revolutions in response to the action of either of said electromagnetic means, and means whereby the torque of said second mentioned electromagnetic means is increased when said member rotates in'a forward direction and is decreased when said member rotates in a backward direction.

9. An electrical instrument comprising a rotatable member, electric motive means adapted to exert two operatively opposing torques on said member, said member being arranged to make a plurality of complete revolutions in response to the action of either of the torques exerted thereon, and

means whereby the rotation of said member in either direction varies one of said torques until the two torques are equal and balanced.

10. An electrical instrument comprising a rotatable disk armature, induction motive means inductively related to said armature for rotatin the armature in a forward direction, induction motive means inductively related to said armature for rotating the armature in a backward direction, said armature being arranged to make a plurality of complete revolutions in response to the action of either of said induction motive means, and means whereby the torque of said second mentioned induction motive means is increased when said armature rotates in a forward direction and is decreased when said armature rotates in a backward direction.

11. An electrical instrument comprising a rotatable disk armature, an induction motive element adapted to rotate said member in a forward direction, a second induction motive element having a movable shading pole and adapted to rotate said member in a reverse direction, and means operatively connecting said shading pole to said rotatable disk armature so that the torque due to said second induct-ion motive element is increased when the armature rotates in a forward direction and decreased when the armature rotates in a backward direction.

12. An electrical instrument comprising a rotatable member, electromagnetic means for developing a torque tending to turn said member in a forward direction, electromagnetic means for-developing a countertorque tending to turn said member in a backward direction, said member being arranged to make a plurality of complete revolutions in response to the action of either of said electromagnetic means, and gearing operatively connecting said member to said countertorque developing means and adapted to cause said countertorque to vary until it equals and balances sald torque, said gearing being proportioned to provlde a predeterminarl tlme interval for the variation of the couiiigei 'torque to equal and balance the torque.

13. An electrical instrument comprising a rotatable member, an electric meter element electrically cooperating with said member to exert directly thereon a torque substantially proportional to the energy flow in an electric circuit, an electric motor element electrically cooperating with said member to exert directly thereon a variable counter torque, and gearing operatively connecting said rotatable member to said electric motor element and adapted to vary the torque thereof until the two torques exerted upon said member are equal and balanced, said gearing beingproportioned to provide a predetermined tlme interval for the variation of the countertorque to equal and balance the torque.

14. An electrical instrument comprising a rotatable disk armature, an induction meter element adapted to exert upon said armature a torque substantially proportional to the energy flow in an electric circuit, an induction motor element of the shaded pole typeadapted to exert a countertorque upon said armature, said motor element having a pivoted shading pole whereby the countertorque exerted upon said armature can be varied, and gearlng operatively connecting said armature to said pivoted shading pole so that forward rotation 'of the armature increases the countertorque of said motor element and backward rotation of said armature decreases the countertorque of said motor element.

In witness whereof, I have hereunto set my hand this th day of June, 1914:.

. CHESTER I. HALL. Witnesses:

H. F. Tnoms, Ron MiiLLER. 

